Oldest surface rock

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The oldest surface rock on the Earth are precambrian, igneous, felsic, and granite ridges and outcrops that were originally formed from the crystallization of molten magma, and are exposed at the surface through erosion and the folding of the Earth's crust, such as in deep valleys, by the scouring of glaciers, and from mountain formation. For example, the Canadian Shield has felsic and granite ridges that are about 2.5 to 3.8 billions years old from the Archean period, and Acasta Gneiss may be even older. There is great difficulty in exactly dating felsic rock formations because of the lack of fossil evidence and the need for more accurate testing and dating methods. More field work and dating is required around the world. There are claims that the Jack Hills and other areas in Australia contain the oldest minerals dated so far. These rocks contain small amounts of zircon crystals that can be accurately dated, but zircon also occurs in other rock formations around the world. Some of the oldest exposed felsic and granite outcrops can be found in the Northwest Territories of Canada, and similar felsic outcrops are also in the Canadian Provinces of Manitoba, Ontario, and Quebec. Other felsic outcrops can be found in Greenland, Africa, and Eurasia. These outcrops are the exposed surface of the craton or crust of the Earth, and can be many acres in size.